Ethers as pollutants in groundwater: the role of reaction parameters during the aquasonolysis

Methyl tertiary butyl ether (MTBE) is one of the most used fuel oxygenates. Oxygenates improve combustion, thereby reducing CO and hydrocarbon emissions in motor vehicle exhaust. MTBE is highly soluble in water and poorly sorbed to carbon based substrates such as soil. An important property of MTBE is its poor biodegradability. The treatment of contaminated groundwater and wastewater by means of conventional biological, chemical and physical techniques turned out to be inefficient. As a matter of principle the degradation of organic compounds by ultrasound in water (aquasonolysis) is practicable as an advanced technology for remediation of waters contaminated with MTBE. The degradation reactions mainly occur in the cavitation bubbles as pyrolytical processes. Under the test conditions, the frequency range between 300 and 800 kHz leads to acceptable degradation values at a power density of 5 W/cm². The degradation was not suppressed by radical scavenger (n-butanol). With concentrations above 25 mg/L MTBE in water, significantly influence of concentration on degradation could be observed.